Mercury exposure hypertension concerns ‘unfounded’

By MedWire Reporters

Mercury exposure is not associated with an increased risk for hypertension, US research shows.

Even at concentrations more than two times the recommended level of exposure, researchers did not observe an association with high blood pressure.

Overall, the findings do not support a need to broaden existing guidelines recommending avoidance of specific higher-mercury seafood to the general population, report Dariush Mozaffarian (Harvard Medical School, Boston, Massachusetts) and colleagues in Hypertension.

Seafood is the major source of exposure to methylmercury. Despite the myriad of benefits of fish consumption, there are concerns that exposure to mercury might increase the risk of coronary heart disease and stroke.

The adverse effects of mercury on hypertension have been largely observed in animal studies and smaller human studies, however.

Using data from two large prospective cohorts, the researchers measured toenail mercury, a marker of long-term methylmercury exposure, in 6045 US men and women free of hypertension at baseline.

The mean toenail concentrations were 0.08 µg/g in the lowest quintile and 0.74 µg/g in the highest quintile.

After adjusting for multiple risk factors, including clinical risk factors, the risk for incident hypertension in the highest versus lowest quintile was not statistically significant (hazard ratio=0.94).

The results were similar when men and women were analyzed separately, as well as in various subgroups.

The researchers note that the mean mercury concentration of individuals in the highest quintile was two times greater than recommended by the US Environmental Protection Agency. Still, no risk for hypertension was observed.

Current guidelines recommend that women of childbearing age and young children avoid seafood with higher mercury concentrations, but Mozaffarian and colleagues say there is no need to extend this to the general population.

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